The present invention pertains to a ballistic resistant article and to a process to manufacture said article.
WO 2008/077605 describes a ballistic resistant sheet comprising a stack of at least 4 monolayers, each monolayer containing unidirectionally oriented reinforcing fibers with a tensile strength of between 3.5 and 4.6 GPa, the fiber direction in each monolayer being rotated with respect to the fiber direction in an adjacent monolayer, an areal density of a monolayer of at least 25 g/m2 and at most 20 mass % of a matrix material preferably selected from the group of polyurethanes, polyvinyls, polyacrylics, polyolefines, polyisoprene-polyethylene-butylene-polystyrene block copolymers or polystryrene-polyisoprene-polystyrene block copolymers. The latter block copolymer is used in the example of WO 2008/077605 and therefore, especially preferred.
However, there is a demand for ballistic resistant sheets with a higher adhesion between the monolayers not only in the unaged state of the ballistic resistant sheet but also after aging the sheet in a climate at elevated values of temperature and relative humidity and/or in a chemically degrading atmosphere, e.g. in an oxygen atmosphere.
Furthermore, there is a demand for ballistic resistant sheets with a lower water pick up after water soak. And there is a demand for ballistic resistant sheets which pass the gasoline soak test.
Finally, if the ballistic sheet is joined to a plate of metal or ceramic, there is a demand for a higher structural integrity of the monolayers behind the plate after a ballistic attack from the plate side. So, there is a demand for a lower degree of delamination between the monolayers behind the plate after a ballistic attack.